Eclipse is not able to launch when we migrate from RCP 4.15 to 4.26

Question

We have migrating from eclipse RCP 4.15 to 4.26. We have created target paltform from referring to p2 repository. (https://download.eclipse.org/eclipse/updates/4.26/R-4.26-202211231800/)

Our Dev-workspace is working fine we are not getting any error. We also did validate plugin in Run-> Run Configuration -> Plugins . It says we all plugins have been resolved. We are able to successfully launch our application.

Now, we built our application using InstallAnyWhere. We tried to launch our application it is not getting started up. It throws an error plugins can not be resolved though these plugins are present in plugins folder.

We tried with felix.filesinstall jar to update our config.ini file with value as osgi.bundles=org.apache.felix.fileinstall@1:start, these will start all the plugins and in eclipse.ini file we have:

-Dfelix.fileinstall.dir=<plugins folder location>
-Dfelix.fileinstall.noInitialDelay=true 
-Dfelix.fileinstall.start.level=1

By, these way our application is able to launch. But, the issue is we need to clear the old-App Data which has few plugins from old RCP ie 4.15.

We are having issue with org.eclipse.core.runtime plugin is giving the issue of classNotfound exception. Ex :

!ENTRY org.eclipse.equinox.app 0 0 2025-01-15 00:19:24.045
!MESSAGE Errors while processing the product providers.
!SUBENTRY 1 org.eclipse.equinox.app 0 0 2025-01-15 00:19:24.045
!MESSAGE Problem creating the provider registered by org.eclipse.core.internal.registry.ExtensionHandle@51d.
!STACK 0
org.eclipse.core.runtime.CoreException: Plug-in org.eclipse.equinox.http.jetty was unable to load class....

We tried couple of solution but none of them is working. Can anyone suggest any solution, how should we solve these.